|The new 1.7-liter diesel.|
GM is applying two new 1.7-liter diesel engines in the new edition Opel Astra. Following Opel’s downsizing strategy, the latest generation common-rail turbo-diesel engines are relatively compact, yet with their high power output per liter and power reserves they boast higher fuel economy and low emissions. These bring the total number of diesels available in the bestselling Astra line to six.
Coupled with six-speed manual transmissions as standard, the new 1.7-liter CDTI ECOTEC unit with 81 kW/110 hp produces 140g of CO2 per kilometer, and the 92 kW/125 hp version 146 g/km. Fuel consumption is an average 5.2/5.4 liters per 100 kilometers (44/45 mpg US).
The engines develop torque of 260 Nm (192 lb-ft) and 280 Nm (207 lb-ft) at 2,300 rpm, respectively.
Both new 1.7 CDTI units in the third-generation Astra feature common-rail direct injection, four-valve technology with swirl control and cooled exhaust gas recirculation with electropneumatic bypass flap control. The cooled EGR system lowers the temperature of the exhaust gas before recirculation further than in a conventional EGR system, thereby achieving an even greater reduction in NOx. (Earlier post.)
However, the constant use of cooled exhaust gas results in the engine taking longer to reach optimal combustion temperatures, possibly resulting in incomplete combustion and an increase in emissions.
The bypass channel can send exhaust gases directly back to the combustion chambers when the engine temperature is low. This helps the engine warm faster, reducing the time for incomplete combustion.
In line with Opel’s downsizing strategy, the compact turbocharged engines have a 79 mm bore and 86 mm stroke, which create a displacement of 1,686 cubic centimeters. The cylinder head is made from light alloy and the engine block from gray cast iron. Its 16 valves are activated directly by two overhead camshafts via flat-base tappets; maximum injection pressure is 1,800 bar. A turbocharger with variable vane technology ensures quick response times.
The diesel engines come with a maintenance-free diesel particulate filter as standard.